Fluidic ball diverter valves are frequently used in missile and space vehicle flight control systems that use reaction jets to control the pitch, yaw, spin rate and other dynamics of a vehicle in flight. In such a flight control system, output from a gas generator or other pressure source is directed into a fluidic amplifier. In response to a control signal provided by the flight control electronics, the fluidic amplifier diverts the gas output into one of two gas paths leading to a pair of nozzles positioned on the outside of the vehicle. One gas path leads to a nozzle having an output to provide a force in one direction. The other gas path leads to a nozzle having an output in the opposite direction. By diverting the gas generator output to one or the other of the two nozzles, the fluidic amplifier provides a positive or negative acceleration affecting the particular flight parameter. Because a pyrotechnic gas generator typically cannot be shut off once initiated, if no change in the flight parameter is dictated by the flight control electronics, the fluidic control system simply oscillates the gas generator output back and forth between the two opposing nozzles. Preferably, the rate of oscillation between the two nozzles is fast enough that the gross body acceleration of the vehicle does not change. To accomplish this, it is not unusual for a fluidic flight control system to change the flow from one nozzle to the other at a rate of 200 times per second or faster.
Design considerations such as the need to minimize the size and weight of the gas generator dictate that non-vented fluidic elements be used to control the gas generator output. Vented fluidic elements have high flow diversion capability, however, they also have a vented reaction zone that would result in a substantial portion of the gas generator output being discharged through an uncontrolled exhaust port. Non-vented fluidic amplifiers do not require a vented reaction region, however, they have a disadvantage in that they are incapable of providing 100% flow diversion. Thus, it is necessary to incorporate an additional device, such as a fluidic ball diverter valve, between the final stage fluidic amplifier and the output nozzles in order to achieve 100% flow diversion. Prior art ball diverter valves are generally constructed by boring a cylindrical chamber into the fluidic amplifier module so that the chamber communicates with both output legs of the fluidic amplifier. After the ball is inserted into the chamber, the ends of the chamber are sealed with caps carrying the ball seats. Although the prior art fluidic ball diverter valves generally achieve the required 100% flow diversion, the prior art valves are heavy and difficult to assemble. The fluidic amplifier module is typically an assembly of individual fluidic element laminae bonded together. Accordingly, prior art fluidic ball diverter valves are prone to failure caused by delamination of the cylindrical ball chamber under the high temperature and pressure of the gas generator output; and since the valve seats are oriented 180.degree. apart, the prior art valves cannot be imbedded within the pressure vessel of the gas generator and, therefore, must be designed to withstand the full gas generator pressure.
What is needed is a gas generator control system incorporating a fluidic ball diverter valve that is compatible with conventional fluidic amplifier elements, yet does not have the cost and weight disadvantages inherent in a cylindrical chamber bored into a laminated fluidic amplifier assembly.